We present Mon-735 , a detached double-lined eclipsing binary ( EB ) member of the \sim 3 Myr old NGC 2264 star forming region , detected by Spitzer .
We simultaneously model the Spitzer light curves , follow-up Keck/HIRES radial velocities , and the system ’ s spectral energy distribution to determine self-consistent masses , radii and effective temperatures for both stars .
We find that Mon-735 comprises two pre-main sequence M dwarfs with component masses of M = 0.2918 \pm 0.0099 and 0.2661 \pm 0.0095 M _ { \odot } , radii of R = 0.762 \pm 0.022 and 0.748 \pm 0.023 R _ { \odot } , and effective temperatures of T _ { eff } = 3260 \pm 73 and 3213 \pm 73 K. The two stars travel on circular orbits around their common centre of mass in P = 1.9751388 \pm 0.0000050 days .
We compare our results for Mon-735 , along with another EB in NGC 2264 ( CoRoT 223992193 ) , to the predictions of five stellar evolution models .
These suggest that the lower mass EB system Mon-735 is older than CoRoT 223992193 in the mass–radius diagram ( MRD ) and , to a lesser extent , in the Hertzsprung–Russell diagram ( HRD ) .
The MRD ages of Mon-735 and CoRoT 223992193 are \sim 7–9 and 4–6 Myr , respectively , with the two components in each EB system possessing consistent ages .